You SHOULD NOT be able to find ANY diverter valve with the option to close ALL the ports. In fact when you have multiple ports and do not use one, the directions ALWAYS say to connect the unused one to an active port and do NOT plug it. The reason being, since humans are inherently lazy, they will start turning off the water with the diverter valve instead of the control valve, which could then introduce all kinds of "weird" problems into the water system. Resulting in more questions here about why are they happening and how do you fix them. Whoever installed a 1 1/2" drain for a shower did not do you any favors because that was NEVER an approved installation.